Date: Mon, 17 Oct 2011 16:29:54 +0100 From: Ben Hutchings <bhutchings@solarflare.com> To: freebsd-net@freebsd.org Subject: Re: TSO broken with jumbo MTU Message-ID: <1318865394.2784.4.camel@bwh-desktop> In-Reply-To: <1317309906.2743.9.camel@bwh-desktop> References: <1317309906.2743.9.camel@bwh-desktop>
next in thread | previous in thread | raw e-mail | index | archive | help
This is the fix/workaround I used:
--- a/netinet/tcp_output.c
+++ b/netinet/tcp_output.c
@@ -1062,9 +1062,7 @@
* The TCP pseudo header checksum is always provided.
* XXX: Fixme: This is currently not the case for IPv6.
*/
- if (tso) {
- KASSERT(len > tp->t_maxopd - optlen,
- ("%s: len <= tso_segsz", __func__));
+ if (tso && len > tp->t_maxopd - optlen) {
m->m_pkthdr.csum_flags |= CSUM_TSO;
m->m_pkthdr.tso_segsz = tp->t_maxopd - optlen;
}
--- END ---
But the correct thing to do may be to change the calculation of t_maxopd
(untested):
--- a/netinet/tcp_input.c
+++ b/netinet/tcp_input.c
@@ -3087,7 +3087,7 @@
tcp_mss_update(struct tcpcb *tp, int offer,
struct hc_metrics_lite *metricptr, int *mtuflags)
{
- int mss;
+ int mss, ts_len;
u_long maxmtu;
struct inpcb *inp = tp->t_inpcb;
struct hc_metrics_lite metrics;
@@ -3212,22 +3212,17 @@
mss = max(mss, 64);
/*
- * maxopd stores the maximum length of data AND options
- * in a segment; maxseg is the amount of data in a normal
- * segment. We need to store this value (maxopd) apart
- * from maxseg, because now every segment carries options
- * and thus we normally have somewhat less data in segments.
- */
- tp->t_maxopd = mss;
-
- /*
* origoffer==-1 indicates that no segments were received yet.
* In this case we just guess.
*/
if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP &&
(origoffer == -1 ||
(tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP))
- mss -= TCPOLEN_TSTAMP_APPA;
+ ts_len = TCPOLEN_TSTAMP_APPA;
+ else
+ ts_len = 0;
+
+ mss -= ts_len;
#if (MCLBYTES & (MCLBYTES - 1)) == 0
if (mss > MCLBYTES)
@@ -3237,6 +3232,15 @@
mss = mss / MCLBYTES * MCLBYTES;
#endif
tp->t_maxseg = mss;
+
+ /*
+ * maxopd stores the maximum length of data AND options
+ * in a segment; maxseg is the amount of data in a normal
+ * segment. We need to store this value (maxopd) apart
+ * from maxseg, because now every segment carries options
+ * and thus we normally have somewhat less data in segments.
+ */
+ tp->t_maxopd = mss + ts_len;
}
void
--- END ---
Ben.
--
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?1318865394.2784.4.camel>